FIGS. 1 and 2 illustrate a Multi-Layer Ceramic Module (MCM), which carries integrated circuits (ICs). The MCM resembles a printed circuit board in the aspects of providing mounts for the ICs and in providing conductors for interconnecting the ICs. The MCM includes a ceramic substrate 3, which contains conductors 6 leading to pads 4 for the ICs in FIG. 2. The conductors are arranged in two layers, such that the conductors on one layer are transverse to those on the other. The transverse conductors cause less cross-talk, because there are fewer flux linkages between transverse conductors than between parallel conductors.
The inventor has found that this configuration presents the following two problems. One, there is a minimum spacing required between conductors. If the conductors are positioned closer than the minimum, the signals on neighboring conductors interfere with each other, and cross-talk occurs. For frequencies in the range of 25 to 100 MegaHertz (MHz), a spacing, indicated in FIG. 2, of 75 micrometers (.mu.M) between conductors which are 25 .mu.M wide has been found necessary in many cases.
Two, there is a limit on the maximum length over which adjacent conductors can run parallel. If the conductors' parallel run exceeds this limit, the mutual coupling between the conductors causes additional cross-talk. In order to eliminate this additional cross-talk, no parallel run should exceed 10 centimeters.